It is common practice to protect the windows of a building, especially those on the ground floor level, from unauthorized entry by means of window guards. Traditionally, such window guards have consisted of heavy gauge wire mesh screens or metal bars which are permanently attached to the building. A permanently installed window guard has a number of disadvantages, however, the primary disadvantage being that in the event of a fire or other emergency, it is not possible to leave the building through the guarded window. One must therefore find another means of escape, which means may not be available.
A number of prior art designs have been introduced to remedy the problems associated with permanent window guards. Each of these prior art designs, however, has its own disadvantages.
U.S. Pat. No. 4,835,906 to Collin discloses a security grill for preventing entrance through a door or window. The top end of the grill is inserted into a retention frame and the bottom end of the grill is pivoted downward and lowered into the frame. The grill is then locked into place using a deadbolt. A disadvantage of this prior art design is that the grill may be completely removed from the frame and, in fact, must be completely removed to exit therethrough. Such a removable grill may easily be lost or stolen, thus allowing for unauthorized access into the building until a new grill can be acquired. Another disadvantage is that the design does not allow for quick and easy egress through the window. Egress requires that the deadbolt be unlocked with a key, which during an emergency may not be readily available. Even if the key is available, the grill must be lifted within the frame and pivoted outward. However, since the metal grill must be resistant to unauthorized entry, it must be soundly constructed and is therefore likely to be heavy. Thus, a physically weak person, such as a child or elderly individual, may not be able to lift the grill enough to pivot it outward, and may therefore be trapped during an emergency.
U.S. Pat. No. 4,384,428 to Cox discloses a screen mounted on a frame by conventional hinges. Flanges on the frame prevent the screen from being pushed outward. To lock the screen in the closed position the end of a bar, which is slidably mounted in the screen, is slid into a corresponding notch in the frame. A disadvantage of this prior art design is that only the end of the bar engaging the frame prevents the screen from being opened. As such, the screen is susceptible to being forced inward by someone desiring unauthorized access to the building. Another disadvantage of this prior art design is that the screen may only be opened inward. In an emergency situation, when a number of people may be gathered around the window attempting to exit the building quickly, it may be easier to open the security screen outward.
U.S. Pat. Nos. 4,993,187 and 5,056,262 to Schweiss et al. disclose a releasable window guard assembly which includes a slideway socket in a frame for receiving a screen. The screen is hinged to the frame by hinge pins, which are attached to the frame and pass through elongated slots in the screen. In the security mode, the screen is trapped behind side plates of the frame. To open the window guard assembly the screen is slid horizontally within the slideway socket, the hinge pins sliding in the elongated slots, until the screen is no longer trapped behind the side plates. The screen is then in the access mode and may be swung outward. A disadvantage of this prior art design is that as the screen is opened, the force of gravity causes the screen to tilt downward. This is true because the hinge pins slide in the elongated slots in the screen as it is being swung outward, the upper hinge pin sliding to the outermost edge of the upper slot and the lower hinge pin sliding to the innermost edge of the lower slot. This tilting of the screen may cause the screen to bind with the bottom of the frame, thereby interfering with the opening of the screen. Moreover, once the screen is swung outward, the tilting of the screen may interfere with the screen from being closed, especially in the case of large, heavy screens.
What is desired, therefore, is a security screen assembly which is installable in the jamb of a building window or door for preventing unauthorized access therethrough, which allows for quick and easy egress from the building, which may be opened without a key, which is operable by a physically weak individual, which may be opened outwardly, which is resistant to forcible attempts to open from the outside, which may be easily opened from the inside, and which may be easily closed.